LOS ANGELES , California -LRB- CNN -RRB- -- Actor Tim Roth is in an abandoned building near downtown Los Angeles , and he 's about to mix things up .

British actor Tim Roth plays a human lie detector on the hit series `` Lie to Me . ''

`` This is a scene where the FBI is interrogating a suspect , '' Roth said . `` I 'm breaking into the interrogation to get information out of him using the sort of techniques that my character espouses as opposed to pressuring him . ''

Roth , who plays Dr. Cal Lightman on the hit Fox series `` Lie to Me , '' is shooting scenes for the season finale , which will air May 13 . His character is an expert on body language and the detection of deception .

`` Our series is based on the idea that we can read what 's going on across your face and if it 's contradicting what you 're actually saying , '' Roth said .

Lightman and his colleague , Dr. Gillian Foster -- played by Kelli Williams -- run `` The Lightman Group . ''

They observe body language and interpret what it means in order to help law enforcement agencies see through the bull .

His character is based on Dr. Paul Ekman , a specialist who reads clues embedded in the human face , body and voice to expose the truth in criminal investigations .

Ekman , who in 2001 was named as one of the most influential psychologists of the 20th century by the American Psychological Association , is a scientific consultant for the show .

Roth says Ekman can be intimidating .

`` He makes me very , very nervous , Paul , you know , '' he said . `` I mean , he 's the sweetest man , as sweet as can be , but when he 's around , you feel like your acting is really being judged . ''

Roth is perhaps best known for his outings with famed director Quentin Tarantino . The British actor pulled off a convincing American accent in the cult classics `` Reservoir Dogs '' and `` Pulp Fiction . ''

He uses his true-Brit accent in `` Lie to Me , '' which debuted in January and is one of the season 's few successful new dramas .

In a review for Entertainment Weekly , critic-at-large Ken Tucker wrote that `` Like ` Monk ' and ` Psych ' and ` The Mentalist , ' ` Lie ' offers us an eccentric who 's brought in by law enforcement to solve crimes . ''

Though he gave the show a B-minus , Tucker praised Roth for `` resist -LSB- ing -RSB- the cuddly/cranky . ''

The show has quickly found its fan base , though ratings have declined slightly since the show was put in its 8 p.m. Wednesday time slot , ahead of `` American Idol . '' -LRB- The first five episodes aired after `` Idol . '' -RRB-

`` I got stopped because one of my lights was out and I was coming back from work and the guy , the cop that stopped me said ` Oh , we watch your show ' and they seemed to enjoy it , '' said Roth .

`` ER '' alum Mekhi Phifer is set to join the cast as an FBI agent for two episodes this season , starting Thursday .

`` I 'm here to kick ass and take names , you know . So it 's kind of different , '' Phifer said . `` It 's fun , you know . Obviously , I carry a gun and I 'm in law enforcement rather than being a doctor . ''

Phifer particularly likes acting in intense scenes with Roth .

`` I have my own way of doing it , '' he said . `` It 's a little different than the way Tim does it . It 's a lot of fun , and we 're having a great time . ''

And will time spent on the show help Phifer better detect when people are lying to him in real life ?

`` It 's going to take a few more episodes , but I 'm pretty perceptive , '' he said .

Roth , however , makes no claims of special powers -- at least when he 's away from the set .

`` I try not to know too much , because it actually is quite extraordinary , '' he says . `` When you watch politicians on TV , you can use the stuff that Paul does to see if they 're lying or not . I try not to take it home . ''

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British actor Tim Roth stars in the hit Fox series `` Lie to Me ''

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Actor best known for his appearances in Quentin Tarantino films

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Roth plays a body language expert who can detect liars

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`` ER '' alum Mekhi Phifer is set to join the cast